| Large volume, complex components of excess activated sludge from municipal wastewater treatment plants have been restricted the reduction and reuse of sludge. The bottleneck of sludge reduction is dewatering because of much of extracellular polymeric substances (EPS). EPS are a complex high-molecular-weight mix coture of excreted by microorganisms, produced by cellysis and hydrolysis, which absorbed organic matter from wastewater. The physical-chemical properties and microbial characteristics of sludge are certainly determined by EPS, which compose 80% of the weight of solid sludge, and the main components of EPS are polysaccharide, protein, nucleic acid, lipid and DNA, etc.Fenton oxidation was used to disintegrate EPS of sludge with its strong oxidation ability. The concentration of polysaccharide, protein and the change of soluble chemical oxygen demand (SCOD) disintegrated from EPS represent the EPS disintegration degree. The objective of this study was to optimize the operational conditions for EPS disintegration with Fenton oxidation. It was shown that the optimal operational conditions were as following: pH2.5, reaction time = 90min, H2O2/Fe2+ (weight dosage ratio) = 8:1 and reaction temperature was about 65~70℃. Under this condition after Fenton oxidation, SCOD, concentration of polysaccharide, protein in the supernate increased from 45.88, 10.96, 11.99mg·L-1 to 684.93, 382.17 and 302.62mg·L-1, respectively. The average diameter and median diameter of sludge particulates reduced from 838.89μm and 859.20μm to 137.22μm and 148.69μm, respectively. As a result, EPS was effectively disintegrated by Fenton oxidation and the sludge was greatly mineralized, which benefited further sludge reduction and utilization.As the development of industry and the improvement of people's living, river sediment was also polluted by heavy metals. Bioleaching was used to remove heavy metals from sludge. The research attempts to put bioleaching to river sediment, which has high alkalinity and much more complex properties. Xiawan Harbor, one of branches of Xiangjiang River, was polluted badly by heavy metals. The sediment used in this experiment was collected from Xiawan Harbor.In order to get ripe activated bacteria, sewage sludge was collected from local municipal wastewater treatment plant to culture, domesticate and enrich bacteria by adding substrates. When the domestication finished, the acididication sludge was inoculated to the sediment to make the bacteria adapt themselves to the extreme environment. Then the bacteria were added to 3% raw sediment at different circumfluence ratios of 0.67, 1, 1.5, 2, 3 and 4 to study the influence of ratio to the heavy metals solubilization. After 4-7d unsealed bioleaching, 1.5 was proved to be an optimum circumfluence ratio. And the heavy metals solubilization efficiency followed as the decreasing order: Zn(87.2%)>Cd(65.0%)>Cu(53.7%)>Pb(31.6%). These data were higher than others respectively. Meanwhile, five sequential extraction procedures indicated that the fatalness of sediment was weakened because metals remaining in the sediment were mainly in stable fractions and became less nonbioavailable. The configurations of sediment changed remarkably after bioleaching, from loosen to tightness, which was likely propitious to sediment dewatering operation.
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